Purpose

The purpose of the CORE-36 questionnaire is to assess the symptoms and/or difficulties experienced by users of mental health services, without focusing on diagnostic systems. It can also be used for research, collecting data on individuals’ evaluations before and after psychotherapy. In summary, the questionnaire covers the assessment of symptoms and the changes that may be observed after psychotherapy, offering a common foundation for evaluating the effect of therapy.

Brief Description

The CORE system consists of three forms:

  1. The CORE questionnaire
  2. A treatment evaluation form
  3. A treatment completion form
    The last two forms are filled out by the therapist. The CORE questionnaire is self-reported and consists of 34 statements related to four dimensions:
  4. Subjective well-being (4 items)
  5. Problems or symptoms (12 items)
  6. Social functioning (12 items)
  7. Risk to oneself or others (6 items)
    The total score, along with the scores from each dimension, reflects the profile of difficulties and psychological reserves of the individuals being assessed. The philosophy of CORE avoids psychiatric categorizations and labels. It was developed through focus group processes, involving mental health professionals and psychotherapists from various therapeutic approaches. The translation into Greek was carried out by a team of ten translators, including a non-professional in mental health, ensuring that the language is understandable and avoiding professional jargon. The questionnaire is an easy-to-use assessment tool for mental health professionals (psychotherapists, psychologists, psychiatrists, social workers, etc.) and researchers.

Sample

The initial sample for the standardization, which consisted of 171 individuals, was divided into two groups:
(a) Users of mental health services, and
(b) Individuals from the general population.
The standardization process for the Greek sample is still ongoing. Results from the standardization of the original questionnaire in the English-speaking population showed excellent psychometric properties (Evans et al., 2002).

Scoring Method

Each item of the questionnaire is scored from 0 to 4, based on the frequency of occurrence. Specifically, the scoring scale is as follows:
• 0: Never
• 1: Rarely
• 2: Sometimes
• 3: Often
• 4: Most of the time or always
The total score for each individual on each dimension is obtained by summing the scores assigned to the corresponding items in that dimension.

Validity

The evaluation of the validity of the questionnaire in English was carried out using seven other established psychometric tools in the same conceptual domain, as per the study by Evans et al. (2002).

Reliability

The statistical analysis for internal reliability, conducted using the Cronbach’s α coefficient in the initial Greek sample, showed values similar to the initial data from the UK standardization sample. Specifically, all Cronbach’s α values were found to be between 0.75 and 0.95. The test-retest reliability study in the UK sample showed values from 0.87 to 0.91 for the total score, indicating that the results have high reliability, as these values fall within a range indicating excellent reliability.

Main Bibliographic Sources

• Core System Group (1998). CORE System User Manual. Website: http://www.coreims.co.uk
• Evans, C., Connell, J., Barkham, M., Margison, F., McGrath, G., Mellor-Clark, J., & Audin, K. (2002). Towards a standardized brief outcome measure: psychometric properties and utility of the CORE-OM. British Journal of Psychiatry, 180, 51-60.
Authors
Core System Group (Adaptation: K. Damaschinidou, E. Avdi, and N. Matziounis)